Essential Cell Biology Chapter 15: Intracellular Compartments and Transport

requires

bioluminescense ______ a great amount of energy

vibrio fischeri

only release their light when it is inside the light organ of squid

quorum sensing

how v. fisheri regulate light production.

autoinducer

small nonpolar signal molecule that is made in the cytoplasm of v. fischeri and diffuses across the plasma membrane

high

autoinducers accumulate at _____ density in the light organ of the squid and diffuse back into the cytoplasm of the cell

receptor; gene regulated protein

autoinducer binds to a _____ and a ________ after diffusing back into cytoplasm of the cell

receptor autoinducer

_____:______ complex binds to the promoter of the luciferase genes

RNA poly

receptor recruits ______ to result in luciferase expression

cell cell signaling types

contact dependent, paracrine, synaptic, endocrine

contact dependent signaling

one cell signals to immediate neighbor using cell surface signal molecules and receptors

paracrine signaling

signal molecule is senses by cells in immediate vicinity of signaling cells

synaptic signaline

mechanism for cell cell signaling used by neurons

endocrine signaling

signal molecule is released by endocrine cells into bloodstream, which disperses the signal to other targets

intracellular

in oder to bind to _________ receptors, signal molecule must be small and hydrophobic enough to pass through the plasma membrane and bind

cell surface receptors

these types of receptors are attached to signal molecule in the plasma membrane
they control intracellular signalling proteins which can alter cell behavior

steroid

hydrophobic signal molecules synthesized from cholesterol

intracellular receptors

steroids are a type of signaling molecules that activate ________

open

without steroid attached, the receptor is in an _____ conformation that won't bind to DNA or activate transcription

steroid

______ binding causes closing of receptor around the steroid molecule

conformation

receptor:steroid complex can bind to DNA once the ________ changes

coactivator proteins

these bind to induce transcription of ..?

phosphorylation and GTP binding

turn on and off signaling proteins

protein kinase

enzyme that covalently attach phosphate to other proteins

phosphorylation

normally activates signaling protein

phosphatase

removes the phosphate from signaling protein

binding

GTP ______ activates signaling protein

hydrolysis

GTP ______ inactivates the signalling protein

cell surface receptor classes

ion channel coupled receptors
enzyme coupled receptors
g protein coupled receptors

ion channel coupled receptors

neurotransmitter gated ion channels

enzyme coupled receptors

enzyme is either the receptor or the receptor associated enzyme. binding of signaling molecule activates an intracelular catalytic domain

g protein coupled receptor

signal molecule binds and causes activation of a GTP binding protein

activates

GTP binding protein diffuses in the membrane to ______ a signaling enzyme

function; abundance

signaling pathways alter cell behavior by changing protein _____ and ______

speed; durability

_____ and ______ determine which strategy is used for cell signaling

slow

______ responses rely on changes in gene expression; time required for transcription/translation slows down behavior

slow

_______ responses are durable and last longer

fast

______ responses rely on altered protein function

fast

_____ responses fade rapidly once the signal is gone

active

____ form of many intracellular signal molecules has a short survival time

too stable

is signaling molecule is __________, the response will persist even after signaling has stopped

short half life

molecules with a _____ _____ ______ will allow signalling to stop rapidly - aka rapid response

rapidly

signaling events that require rapid responses involve proteins that are ____ turned over/activated

scaffold proteins

attach to receptors to help cells avoid crosstalk between signaling pathways

inactive

______ intracellular signaling proteins assemble on scaffold protein

signaling complex

when signal is received by receptor, it is relayed from one signaling protein to the next via ____ ______ (for scaffolding protein)

signaling complex

ensure rapid signal delay and prevent cross talk

inactive

some intracellular signal proteins are free in cytosol when receptor is ______

receptor phosphorylation

provides docking sites for intracellular signal proteins that relay signals to downstream targets

phosphoinosides

generate docking sites for some signaling complexes

phosphorylated

once phosphoinositides are _______, they can allow signaling complexes to form on the membrane

integration

multiple signals can impinge on one protein via _______

modular interaction domains

phosphotyrosine binding domain, src homology 2, pleckstrin homology, src homology 3

PTB domain

attaches to phosphorylated tyrosine residues on activated receptors

SH2 domain

binds to phosphotyrosine

PH domain

attaches to particular phosphoinositides on the inner leaflet of the plasma membrane

SH3 domain

binds to other proteins to assemble signaling complexes

domain combination

______ ________ dictates which proteins the signaling protein binds and therefore the role of the signaling protein

amino acids

each SH2 binds to phosphotyrosine and _______ of the protein that it recognizes

phosphorylation

many signaling proteins have several SH2 domains that only recognize specific protein ________ patterns

JAK

cytokine receptors attach to ______

dimerization

cytokine binding induces receptor ____

trans phosphorylation

receptor dimerization triggers _______ ________ of JAK

JAk

phosphorylates cytokine receptor

STAT

binds receptor with SH2 domains and becomes phosphorylated

STAT

dissociates and dimerizes using SH2 domains

STAT dimer

induces expression of genes that help fight expression upon being transferred into the nucleus

JAK STAT

signaling that is important to the immune system

autoimmune disease

diseases that result from unregulated immune response

tofacitinib

JAK inhibitor that enters T cells and binds to JAK and shuts down JAK STAT signaling

nonreceptor tyrosine kinase

kinases that signal via JAK STAT pathway

receptor tyrosine kinase

kinases that are part of the receptor of cytoplasmic domain

dimerizes

in RTK, signaling molecule binding ____ the receptor

crossphosphorylate

in RTK, receptor monomers __________ to initiate signaling

EGF

epidermal growth factor ; mitogen

growth factor

control cell growth by regulating protein synthesis

mitogen

stimulate mitosis

EGF

binds and activates the epidermal growth factor receptor

phosphorylated

when EGF binds to EGFR, EGFR is _______

Grb2

docks at the EGFR phosphototyrosine using SH2 domain

Sos

Ras GEF that is bound to Grb2 via SH3 domain

GDP; GTP

Sos activates Ras by catalyzing _____ to ______ `

MAP kinase cascade

major target of Ras:GTP

Ras:GTP

this complex activates Raf kinase

Raf

phosphorylates the Mek kinase

Mek

phosphorylates Erk kinase

Erk

phosphorylates and activates downstream regulators of mitosis

macrophages

MAP kinase signaling is required for survival of ______

PI phosphorylation

carried out by PI kinases and generates phospoinositides

phosphoinositides

PI with phosphate at one or more carbons of the inosol head group

PI3 kinase

phorphorylates phosphatidylinositol at 3rd , 4th, and 5th positions
important for cell survival

tyrosine

survival factor binds receptor ______ kinase

PI3 kinase

recruited by phosphorylated receptor that has survival factor bound to it

bcl2

bad inactivation causes release of the apoptosis inhibitor ____

GPCR

largest family of cell surface receptors in eukaryotic cells

GPCR

membraneproteins with 7 alpha helical transmembrane domains

trimeric

G proteins are _____

alpha

_____ subunit is the GTP-binding domain in G protein coupled receptors

beta; gamma

_____ and _____ subunits control signalling in G protein coupled receptors

trimeric G proteins

are anchored to inner leaflet of plasma membrane via lipid modification of alpha and gamma subunits

loosely attached

in absense of extracellular signal molecule, GPCR is _____ _______ to an inactive trimeric G protein

extracellular signal molecule

_____ ______ ______ binds to extracellylar domain of GCPR after the inactive G protein is bound to GDP

alpha subunit

GPCR activates the _______ of the trimeric G protein

GEF

activation of GPCR causes ____ so that the alpha subunit can bind to GTP

beta gamma

activated alpha subunits can activate the _____ subunit of G protein

cAMP

synthesized from ATP by adenylate cyclase

cAMP

type of second messenger in cells

Gs

trimeric G protein that stimulates cAMP production

Gi

trimeric G proteins that inhibit cAMP production

AMP

when signaling is finished, cAMP phosphodiesterase cleaves cAMP to ____

adenylate cyclase

converts ATP to cAMP

high

_____ cAMP = electrolyte and fluid loss

cAMP

controls fluid balance across epithelial cells

pertussis toxin

inactivates Gi and causes host cell to increase adenylate cyclase activity and cAMP

ACase

bacterial adenylate cyclase that enters the cells and raises cAMP

Ptx and ACase

toxins produced from whooping cough; trigger increase cAMP in respiratory epithelials cells that lead to fluid loss

Gq

G proteins that signal through the enzyme phospholipase C

IP3 and DAG

products of PI(4,5)P2

IP3

phosphate that is soluble in the cytoplasm of the cell
diffuses away from the membrane and takes part in downstream signaling events

DAG

triggers downstream signaling events

calmodulin

Ca2+ regulated signaling protein that has two globular domains connected by an alpha helix

T cells

cells of the immune system rely on calmodulin signaling

antigen

when T cell meets _______, it produces the signaling molecule interleukin 2

NFAT

binds DNA at the promotor for IL2 gene and allows cell to express IL2 which elicits cell division

cyclosporin A

immunosuppressive drug

proteolysis

cell cell signaling event where receptor typically signals for the cleavage and/or degradation of a cellular protein

lateral inhibition

process where cells block each other from developing into the same cell type

delta

when activated by _____, notch blocks cell specialization

notch

represses expression of delta

delta

the _____ expressing cell will develop into specialized nerve cells

NFkB

proteolytis regulated signaling that is initiated by the signaling protein tumor necrosis factor alpha

TNFalpha

major signaling protein involved in triggering inflammation as response to infection
released by macrophages upon infection
is a trimer